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Esophagus
| Lymph = | MeshName = oEsophagus | MeshNumber = A03.556.875.500 | Dorlands = three/000036999 | DorlandsID = Esophagus }} The esophagus or oesophagus (see American and British English spelling differences), sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. The word esophagus is derived from the Latin oesophagus, which derives from the Greek word oisophagos (οισοφάγος), lit. "what carries and eats". In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through a hole in the thoracic diaphragm called the esophageal hiatus at the level of the tenth thoracic vertebrae (T10). It is usually 25-30 cm long which connects the mouth to the stomach. It is divided into cervical, thoracic, and abdominal parts. Functions of the esophagus Food is passed through the esophagus by using the process of peristalsis. Specifically, it connects the pharynx, which is the body cavity that is common to the digestive factory and respiratory system with the stomach, where the second stage of digestion is initiated. The esophagus is deeply lined with muscle that acts with peristaltic action to move swallowed food down to the stomach. Due to the fact that the esophagus lacks the mucus lining like that of the stomach, it can get irritated by stomach acid that passes the cardiac sphincter. Histology The layers of the esophagus are as follows: * mucosa ** nonkeratinized stratified squamous epithelium: is rapidly turned over, and serves a protective effect due to the high volume transit of food, saliva and mucus. ** lamina propria: sparse. ** muscularis mucosae: smooth muscle *''submucosa: Contains the mucous secreting glands (esophageal glands), and connective structures termed papillae. * ''muscularis externa (or "muscularis propria"): composition varies in different parts of the esophagus, to correspond with the conscious control over swallowing in the upper portions and the autonomic control in the lower portions: ** upper third, or superior part: striated muscle ** middle third, smooth muscle and striated muscle, ** ''inferior third: predominantly smooth muscle. * adventitia Gastroesophageal junction The junction between the esophagus and the stomach (the '''gastroesophageal junction' or GE junction) is not actually considered a valve, although it is sometimes called the cardiac sphincter, cardia or cardias, but is actually more of a stricture. See also * Achalesia * Esophageal * Esophageal disorders * Esophageal dysphagia Additional images Image:Esophagus_path.jpg|H&E stain of biopsy of normal esophagus showing the stratified squamous cell epithelium Image:Illu esophageal layers.jpg |Layers of the esophagus. Image:Mid_esophageal_mass.jpg|Mid-esophageal mass Image:Illu stomach2.jpg|Stomach Image:Digestive system showing bile duct.png|Accessory digestive system. Image:Illu dige tract.jpg|Organs of the digestive tract. Image:Illu esophagus.jpg|Esophagus Image:Gray384.png|Section of the neck at about the level of the sixth cervical vertebra. Image:Gray503.png|Transverse section of thorax, showing relations of pulmonary artery. Image:Gray994.png|Sagittal section of nose mouth, pharynx, and larynx. Image:Gray1032.png |The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind. | Image:Gray1033.png|Section of the human esophagus. Moderately magnified. Image:Gastro-esophageal jxn.JPG|Microscopic shot of a cross section of human gastro-esophageal junction wall. References External links * Category:Digestive system Category:Thorax